Intensive analysis of first birth intervals, including delayed births, for successive cohorts of women who were first married between 1950 and 1970, through the application of recent methodological advances to the multivariate analyses of life table relationships. Life tables and proportional hazards model analytical techniques will be used to provide basic descriptive information about the shape of first birth interval curves and also to analyze the influence of selected socio-economic and demographic correlates and determinants of first birth intervals. The data base would be the 1973 National Survey of Family Growth (NSFG), which included 7,644 women married less than three times and whose reproductive careers occurred during a period when first birth intervals shortened and then lengthened.